update for Issue #2064 (changed docblocks which return $this or only call a method that returns $this to @return CI_DB_class_name)
diff --git a/system/database/DB_forge.php b/system/database/DB_forge.php
index 59c3baf..fd224c4 100644
--- a/system/database/DB_forge.php
+++ b/system/database/DB_forge.php
@@ -229,7 +229,7 @@
*
* @param string $key
* @param bool $primary
- * @return object
+ * @return CI_DB_forge
*/
public function add_key($key = '', $primary = FALSE)
{
@@ -266,7 +266,7 @@
* Add Field
*
* @param array $field
- * @return object
+ * @return CI_DB_forge
*/
public function add_field($field = '')
{